展开 (1+3cos(x))^2

解答

展开

(1 + 3 cos (x))^{2}

1 + 6 cos (x) + 9 cos^{2} (x)

求解步骤

(1 + 3 cos (x))^{2}

使用完全平方公式:

(a + b)^{2} = a^{2} + 2 ab + b^{2}

(1 + 3 cos (x))^{2} = 1^{2} + 2 \cdot 1 \cdot 3 cos (x) + (3 cos (x))^{2}

= 1^{2} + 2 \cdot 1 \cdot 3 cos (x) + (3 cos (x))^{2}

化简

1^{2} + 2 \cdot 1 \cdot 3 cos (x) + (3 cos (x))^{2} : 1 + 6 cos (x) + 9 cos^{2} (x)

= 1 + 6 cos (x) + 9 cos^{2} (x)

e x p an d \frac{3 - x}{( x - 2 ) ^{4}}

e x p an d \frac{x}{( x ^{2} + w ^{2} ) ( x ^{2} + 4 )}

e x p an d (cos (x) + cos (y))^{2}

e x p an d \frac{x ^{m} ( x ^{m} + 1 )}{2}

s im pl i f y (1 - \frac{2}{x + 1}) (3 x^{3})